<?php

namespace App\Models;

use Carbon\Carbon;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\MorphMany;
use Illuminate\Database\Eloquent\SoftDeletes;

class Phase extends Model
{
    use SoftDeletes;

    protected $fillable = [
        'project_id', 'name', 'description', 'order', 'color', 'progress_percent',
        'planned_start', 'planned_end', 'actual_start', 'actual_end',
        'baseline_start', 'baseline_end',
    ];

    protected $casts = [
        'planned_start' => 'date',
        'planned_end' => 'date',
        'actual_start' => 'date',
        'actual_end' => 'date',
        'baseline_start' => 'date',
        'baseline_end' => 'date',
    ];

    public function project()
    {
        return $this->belongsTo(Project::class);
    }

    public function layers()
    {
        return $this->hasMany(Layer::class);
    }

    public function progressUpdates()
    {
        return $this->hasMany(ProgressUpdate::class);
    }

    public function currentLayer()
    {
        return $this->hasOne(Layer::class)->latestOfMany();
    }

    public function features()
    {
        return $this->hasManyThrough(Feature::class, Layer::class);
    }

    public function media()
    {
        return $this->morphMany(Media::class, 'mediable');
    }

    public function images()
    {
        return $this->morphMany(Media::class, 'mediable')->where('category', 'image');
    }

    public function tasks()
    {
        return $this->hasMany(Task::class);
    }

    public function progressSnapshots(): MorphMany
    {
        return $this->morphMany(ProgressSnapshot::class, 'trackable');
    }

    /**
     * Deviation in days: positive = delayed, negative = early
     */
    public function getDeviationDaysAttribute(): ?int
    {
        if (! $this->planned_end) {
            return null;
        }
        $end = $this->actual_end ?? now()->toDateString();

        return $this->planned_end->diffInDays($end, false);
    }

    /**
     * Start deviation: positive = delayed start, negative = early start
     */
    public function getStartDeviationDaysAttribute(): ?int
    {
        if (! $this->planned_start) {
            return null;
        }
        $start = $this->actual_start ?? now()->toDateString();

        return $this->planned_start->diffInDays($start, false);
    }

    /**
     * Planned progress at a given date (linear interpolation)
     */
    public function getPlannedProgressAtAttribute(?Carbon $date = null): float
    {
        $date = $date ?? now();

        if (! $this->planned_start || ! $this->planned_end) {
            return 0;
        }

        if ($date <= $this->planned_start) {
            return 0;
        }
        if ($date >= $this->planned_end) {
            return 100;
        }

        $totalDays = $this->planned_start->diffInDays($this->planned_end);
        $elapsedDays = $this->planned_start->diffInDays($date);

        return round(($elapsedDays / $totalDays) * 100, 2);
    }

    /**
     * Schedule Performance Index (SPI) = EV / PV
     */
    public function getSpiAttribute(): ?float
    {
        $pv = $this->planned_progress_at; // Planned Value
        $ev = $this->progress_percent;     // Earned Value (current progress)

        if ($pv <= 0) {
            return null;
        }

        return round($ev / $pv, 2);
    }

    /**
     * Check if phase is on track (SPI >= 0.95)
     */
    public function getIsOnTrackAttribute(): ?bool
    {
        $spi = $this->spi;
        if ($spi === null) {
            return null;
        }

        return $spi >= 0.95;
    }
}
